Relationship of Ultraweak Luminescence Intensity with Physiological Metabolism of Maize Seeds during Artificial Aging

The seeds of maize （Zea mays L.） variety Zhengdan 958 were used to study the change of ultraweak luminescence （UWL） intensity and its relationship with seed vigor, relative electric conductivity and ATP content during artificial aging. The results indicated that the germination percentage, germination potential, germination index, UWL intensity and ATP content decreased gradually, while the relative electric conductivity increased with the prolongation of artificial aging. The correlation analysis showed that UWL intensity was significantly positively correlated with ger- mination percentage, germination potential, germination index and ATP content, while significantly negatively correlated with relative electric conductivity. It was concluded that UWL was closely related to the energy level symbolized by ATP content, and as a fast nondestructive physical indicator with better sensitivity, it could be applied into the study of seed vigor nondestructive testing.

Effects of Artificial Aging on Seed Vigor and Ultraweak Luminescence of Wheat Seeds

In order to ascertain the effect of artificial aging on ultraweak lumines- cence （UWL） and the correlation between UWL and seed vigor, and explore a new way of seed vigor non-destructive testing, seeds of wheat variety ‘Jimai 22＇ were used to study the change of UWL intensity and its relationship to seed vigor and ATP content during artificial aging. The results showed that with the extension of artificial aging time, the germination percentage, germination potential, germination index, UWL intensity and ATP content decreased gradually; after artificial aging for 48 h, they were reduced by 19.19%, 34.34%, 38.78%, 27.77% and 13.84%, re- spectively, compared with CK. Correlation analysis indicated that the UWL intensity was significantly positive correlated with germination percentage, germination poten- tial, germination index and ATP content. It was concluded that UWL as a fast, non- destructive and sensitive detection method could be applied in the study of seed vigor non-destructive testing.

Resistance -induced Effect of Several Chemical Reagents on Cucumber against Pseudoperonospora cubensis

[ Objectlve] The paper was to compare the induced resistance of several chemicals on cucumber against Pseudoperonospora cubensis [ Method ] When the cucumber seedlings grew to 4-leaf stage, the second true leaf was treated with salicylic acid, oxalate, chitosan, calcium nitrate and Na2HPO4, the activity of protective enzymes in the third leaf was determined after 7 d. At the same time, inoculation test was also conducted after induced treatment, and the disease condi- tion was coumed. [ Result ] These chemical treatments promoted protective enzyme activities （POD, SOD, PAL, PPO） in different degree, improved the ultra-weak luminescence, and reduced the disease index of cucumber leaves. [ Conclusion] Five chemical treatments expressed good effects on induced resistance. Among the treatments, oxalate had the best induced effect, followed by salicylic acid, chitosan, Na2 HPO4 and calcium nitrate.